Functionality: This watch uses a custom Samsung app store and uses the Tizen OS instead of the more standard Google app store and Wear OS that most other android watches use. That is not a problem when it comes to watches like this one though as you can make calls, receive calls, take and write texts, receive and write e-mails, you can get driving directions with a map app, there is a web browser that works well, heart rate monitor, sleep monitor, exercise apps, you can watch youtube videos and it looks great, you can get notifications form all social media sites, and much more, this watch can do pretty much anything you want in a smart watch, excellent. This watch is waterproof, you can swim with it, take a shower with and dive with it. The battery life is very good IMO on this 46mm model, I am getting 3-4 days out of it and I use it for heavy tasks like calls and video along with maps too. It is very easy to charge with the included wireless charging stand too. The only downside is that if you are not using one of the newer Samsung phones you need to do a few workarounds to get texts to work properly. I was not using a Samsung phone and can report I am still extremely impressed by the functionality.
Expandability: There are hundreds of watch cases, bezels and watch bands(leather, rubber and metal/steel) that you can buy for a low fee to customize the entire look of this watch. You will not be disappointed at all in this department, nice looks for male and female users and all kinds of funny prints and also professional looks that can make the watch look almost like a rolex, no joke form a distance.
Overall: This is the best smart watch you can get in 2019 IMO when comparing it to watches I have tried out, seen in stores and I also read many reviews form watch/tech sites and many agree with this opinion. The only cons are that some functions that have to do with texting and e-mail do not work out of the box for non-Samsung phone users. You need to download some 3rd party apps to get that up to par. The pros heavily outweigh those slight flaws though, so I recommend this watch to anybody looking for a smart watch this year.
Score: 9.5/10 This watch does everything I dreamed of a smart watch being able to do & more. The only slight flaw is that if you are not using a non-Samsung brand phone or older Samsung phone you probably will have to do a little extra to get it to properly handle e-mails & texts(download a few extra apps), but other than that is does everything at top notch out of the box and I love it!